Aliphatic ceramics dispersant

ABSTRACT

The invention provides dispersed inorganic mixed metal oxide pigment compositions in a hydrocarbon media utilizing a dispersant having polyisobutylene succinic anhydride structure reacted with a non-polymeric amino ether/alcohol to disperse a mixed metal oxide pigment in the media. The metal oxide pigment is of the type used to color ceramic or glass articles. A milling process using beads is also described to reduce the mixed metal oxide particle size to the desired range. A method of using the mixed metal oxide dispersion to digitally print an image on a ceramic or glass article using the dispersion jetted through a nozzle and subsequently firing the colored article is also described.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase entry under 35 U.S.C. 371 ofPCT/US2017/065319 filed Dec. 8, 2017, which claims the benefit of U.S.Provisional Application No. 62/432,064 filed Dec. 9, 2016.

FIELD OF INVENTION

The dispersants and dispersed mixed metal oxide pigment compositions areuseful for the coloration of ceramic articles and glass. The dispersedpigments are those of the type that develop their coloration during hightemperature ceramic firing of a coating on the ceramic article or glass.The dispersed pigments are desirably suitable for jetting through anozzle during a digitally controlled printing operation. The dispersantsfrom polyisobutylene coupled to a dicarboxylic anhydride (such as maleicanhydride) and then reacted with a non-polymeric amino ether/alcohol.

BACKGROUND OF THE INVENTION

Civilizations have made a variety of ceramic articles such as cookingand serving vessels, water and other fluid containers, tiles, bricks,etc., for thousands of years. These were typically colored or decoratedwith metal oxide type pigments that developed colors or more intensecolors during an elevated temperature firing of the pigment and ceramicarticle. The metal oxide type coloration pigments were thought tochemically interact and interpenetrate and develop colors at hightemperatures with the ceramic composition and/or with more glassycompositions sometimes applied with the coloration pigments orsubsequently applied. The more glassy compositions were often to provideimpermeable or barrier properties to the outer surface of the ceramicarticle (to protect the ceramic article from environmental materialswith which it might come into contact).

With conventional organic pigments and the few inorganic pigments (e.g.,TiO₂, silica, and talc) in polymeric organic binder, the particle sizeand particle uniformity are very important to achieve consistent andintense coloration. Inorganic mixed metal oxide pigments used ininorganic ceramic coloration are generally not as well understood asorganic pigments. The particle size of the inorganic mixed metal oxidepigments generally has not been studied and controlled to the extentthat particle sizes of pigments has been controlled for use in polymericorganic coatings and inks.

U.S. Pat. No. 3,846,127 discloses an imaging system comprisingphotosensitive pigment dispersed in an insulating binder and exposed toactinic electromagnetic radiation. The pigment particles are treatedwith polyisobutylsuccinic anhydride or derivatives thereof before beingincorporated in the imaging layer.

WO 87/05924 discloses dispersions of solids in organic liquids where thedispersant has a molecular weight from 500 to 10,000. The solids can beinorganic or organic pigments. The use can be in paints, enamels,printings inks and other surface coatings, including articles made fromplastics and rubber. Examples 1-13 include polyisobutylene baseddispersants.

US 2008/0182927 discloses PIBSAs as dispersants for metal oxidenanoparticles in liquid including toluene, xylene, mineral spirits,hexanes, and phenoxyisopropanol. The metal oxides mentioned by nameinclude those of zinc, zirconium, cerium titanium, aluminum, indium andtin. In their examples, they used alumina with a particle size of 30 nm,zirconia with a particle size of 15 nm, ceria with a particle sizeslightly less than 100 nm, and zinc oxide with a particle size of 30 nm.

SUMMARY OF THE INVENTION

More recently the printing industry has shifted away from traditionalprinting methods and is using digital printing instead. When consideringconverting mixed metal oxide dispersions for coloring ceramic articlesfrom conventional gravure or screen-printing processes, these inkformulations require better dispersants in order that they meet all therequirements needed to be jetted using a digital printer. There is alsoa need to quickly and efficiently reduce the particle sizes of inorganicmetal oxide pigments by milling from their current commerciallyavailable sizes to D₅₀ number average particles sizes of less than 600nm so the particles can be jetted through small openings of the ink jetprintheads. While many pigments for conventional coatings or inks tendto be organic and have densities within 10 or 20 wt. % of the continuousorganic media, mixed metal oxide pigments can have densities of 2 to 4times that of the continuous phase, making such mixed metal oxidepigments much harder to keep dispersed as colloidal particles in anorganic media.

A dispersant for mixed metal oxides has been identified as a reactionproduct of polyisobutylene with maleic acid and/or anhydride andsubsequent reaction with a non-polymeric amino ether/alcohol. It hasbeen found that the above dispersants show excellent ability tofacilitate milling and disperse inorganic pigments (preferably mixedmetal oxide pigments) to produce colloidally stable mixed metal oxidedispersions in non-aqueous, non-polar organic (hydrocarbon) media basedink jet inks for the coloration of ceramic tiles and glass using ink jetink printers. Thus, according to the present invention, there isprovided a composition comprising a particulate solid; a continuousmedia selected from aliphatic hydrocarbon, or blends thereof; and adispersing agent being a reaction product of polyisobutylene with maleicacid and/or anhydride and subsequent reaction with a non-polymeric aminoether/alcohol.

Also provided is a method for milling the mixed metal oxide pigmentsusing the reaction product of polyisobutylene with maleic acid and/oranhydride and subsequent reaction with a non-polymeric aminoether/alcohol in minimal time and with minimal contamination of themixed metal oxide dispersion by wear components from the mill and beadsused in milling. The dispersant functions to facilitate milling bycolloidally stabilizing new surfaces created by milling and preventingaggregations of milled particles into larger aggregates. Also providedis a method of formulating a digital ink for ink jet printing using thereaction product of polyisobutylene with maleic acid and/or anhydrideand subsequent reaction with a non-polymeric amino ether/alcoholdispersant of this disclosure. Also disclosed is a method of digitallyprinting using an ink jet printer and an ink with mixed metal oxidepigments and a reaction product of polyisobutylene with maleic acidand/or anhydride based dispersant.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to the use of a class of dispersants in ceramicink jet inks formulations, to dispersions containing such dispersantstogether with a particulate solid (mixed metal oxides) and a hydrocarbonmedium (aliphatic and optionally aromatic hydrocarbon, or blendsthereof), and compositions comprising a particulate solid, a hydrocarbonmedium and a dispersant and to their use in ceramic ink jet inks andmill-bases. Many formulations such as inks, paints and mill-basesrequire effective dispersants for uniformly distributing a particulatesolid in a non-polar organic (hydrocarbon) medium.

In one embodiment, the invention relates to a pigment dispersioncomposition comprising:

a) 20-79 wt. % of continuous liquid hydrocarbon media, includingaliphatic hydrocarbon, non-polar fatty acid ester medium or combinationsthereof;

b) 20-60 wt. % of a mixed metal oxide ceramic pigment in particulateform that develops its full color intensity and hue after firing atelevated temperatures; and

c) 1-20 wt. % of a dispersant being a reaction product ofpolyisobutylene with maleic acid and/or anhydride forming a PIBSA(polyisobutylene succan) that is then reacted at a molar ratio of 0.9:1to 1.1:1 of succan anhydride groups of the PIBSA with a non-polymericamino ether/alcohol.

In one embodiment, the invention relates to a process for milling aninorganic mixed metal oxide particulate, having a dry powder volumeaverage particle diameter D₅₀ in excess of 2 micron, in a continuousnon-polar organic (hydrocarbon) medium to a D₅₀ particle size of lessthan 600 nanometers, said process comprising:

a) blending said continuous medium, said inorganic mixed metal oxideparticulate, wherein said inorganic mixed metal oxide particulate is amixed metal oxide pigment that develops its color intensity and hueafter firing at elevated temperatures; optionally including a vitreousglaze material, having a dry powder volume average particle diameter inexcess of 2 micron, and a dispersing agent being a reaction product ofpolyisobutylene with maleic acid and/or anhydride and subsequentreaction with a non-polymeric amino ether/alcohol;

b) milling said mixed metal oxide pigment dispersed with said dispersingagent in said continuous medium using a bead mill for 5 minutes to 60hours; and

c) confirming the volume average particle diameter D₅₀ is less than 600nanometers.

In one embodiment, the invention relates to a process for digitallyprinting on ceramic article or glass article substrate using an inkjetted through a nozzle comprising:

a) providing a mixed metal oxide dispersed in a continuous non-polarorganic (hydrocarbon) medium with a dispersing agent being a reactionproduct of polyisobutylene with maleic acid and/or anhydride;

b) jetting said mixed metal oxide dispersed in said continuous mediumusing said dispersing agent onto said substrate to form a pigmenteddigital image (optionally on a pre-glaze layer(s) on a ceramic surface),wherein said pigmented digital image on said substrate develops into acolored image upon firing said ceramic substrate or heating said glasssubstrate to provide tempering or annealing;

c) optionally applying a glaze over said digital image; and

d) heating said ceramic article at an elevated temperature or heatingsaid glass article to anneal or temper it, wherein said image from mixedmetal oxide develops optimal color intensity upon heating to its color.

It is understood that the dispersing agent is generally as describedabove and being a reaction product of polyisobutylene with maleic acidand/or anhydride forming a PIBSA (polyisobutylene succan) and thenfurther reacted with a non-polymeric amino ether/alcohol.

Definitions

Non-polar organic (hydrocarbon) media will mean liquids that arepourable at 25° C. and 670 mmHg atmospheric pressure, derived primarilyfrom carbon and hydrogen and optionally having small amounts of oxygenand nitrogen. Desirably, the amount of oxygen and nitrogen combined willbe less than 10 wt. % of the atoms in the organic media. Non-polarorganic (hydrocarbon) will exclude low molecular weight hydrocarbonsthat have a boiling point of less than 40, 50 or 60° C. at 670 mmHgatmospheric pressure or binary compounds such as carbon oxides,carbides, carbon disulfide, phosgene, carbonates, etc. Desirablenon-polar organic media include aliphatic and aromatic hydrocarbons.Hydrocarbon will generally mean compounds formed exclusively or almostexclusively (e.g. >95, >98, or >99 wt. %) from carbon and hydrogen. Theresidual 0, ≤1, ≤2, or ≤5 w. % may be other elements such as oxygen,nitrogen, halogens, etc. Desirably, the amount of aromatic rings is lessthan 20, more desirable less than 10, and preferably less than 5 wt. %of the organic media. The term hydrocarbyl will refer to monovalenthydrocarbon groups that may optionally include other heteroatoms (suchas O, N, F, Cl, and Br) in conventional or specified amounts. The termhydrocarbylene will refer to divalent hydrocarbon groups that mayoptionally include other heteroatoms in conventional or specifiedamounts.

We will use the term hydrocarbyl to describe a hydrocarbon type groupwith one hydrogen removed. Hydrocarbyl in this specification will meanhydrocarbon like and can desirably include up to one oxygen and/ornitrogen for every four carbon atoms in the group, but preferably isjust carbon and hydrogen atoms. For the avoidance of doubt, when we arecounting carboxylic acid or carbonyl groups, we will count an anhydrideof a dicarboxylic acid and an imide as having two carbonyl groups.

Desirably, the dispersions of mixed metal oxides, dispersing agent, andcontinuous media is adjusted to desirable viscosities for ink jetprinting. Desirable viscosities include from about 1, 2 or 3 to about15, 20, 30 or 50 cps at @ 30 s⁻¹ at 25° C. as measured with a cone andplate type viscometer, such as the TA 2000EX Rheometer with a 2aluminium cone.

In one embodiment, the molecular weight of the PIBSA portion of thedispersant being a reaction product of polyisobutylene with maleic acidand/or anhydride and having a weight average molecular weight from 400to 3000 g/mole, and preferably is from 500 to 2400 or 2500 g/mole asmeasured by GPC (gel permeation chromatography) using polystyrenestandards.

In one embodiment, an ink comprises a dispersion of a mixed metal oxidein a non-aqueous, non-polar organic (hydrocarbon) media. In anotherembodiment, the ink is in the form of an ink jet ink.

In another embodiment, the ink is in an ink jet printer cartridgecomprising a chamber which contains the ink including the continuousmedia, the dispersant, the mixed metal oxide pigments and any optionalcomponents to the dispersion or the ink.

Various preferred features and embodiments will be described below byway of non-limiting illustration.

The reaction product of polyisobutylene with maleic acid and/oranhydride (also known as PIBSA—polyisobutylene succinic anhydridereaction products) may be prepared by processes known to a skilledperson. They will comprise at least one polyisobutylene chain and atleast one unit derived from coupling the maleic acid and/or anhydride tothe polyisobutylene. The maleic acid and/or anhydride will often losethe double bond or the double bond will migrated during coupling to aslightly different location. As these reactions typically occur above100° C. or 150° C., any maleic acid is generally converted to maleicanhydride. The term succinic is used in lieu of maleic and refers to thesame grouping of atoms but with the carbon-to-carbon double bondconverted to a carbon-to-carbon single bond in the coupling reaction.The maleic anhydride ring can open forming maleic acid during thecoupling reaction or after the coupling reaction or vice versus ifmaleic acid is used as the starting material. The reaction product ofpolyisobutylene with maleic acid and/or anhydride is sold commerciallyby many parties in the lubricating oil field (e.g., Orinite in the USand China, Texas Petroleum Corp., and Daelim in South Korea) and inemulsion explosives as polyisobutylene succinic anhydride reactionproducts.

There is an article on characterizing such materials titled“Characterization of Polyisobutylene Succinic Anhydride ChemistriesUsing Mass Spectroscopy,” J. of Applied Polymer Science, Vol. 124, Issue4, pp 2682-2996, published 2 Nov. 2011 by Edgardo Rivera-Tirado, et al.One process called the ene-type reaction does not require chlorine anduses a material called highly reactive polyisobutylene (PIB) which has ahighly reactive terminal vinylidene group (called high vinylidene PIB).This first process is described in EP 1585773 and U.S. Pat. No.6,077,909 (e.g., col. 6, line 14 through col. 7, line 62 and col. 9,line 10 through col. 10, line 11). High vinylidene PIB is made by aparticular polymerization process. A second process is called theDiels-Alder type reaction and chlorine during this reaction is useful.This second process uses a low vinylidene PIB. The Diels-Alder typereaction can be higher temperature (e.g., 180-250° C.) under an inertgas (low in oxygen nitrogen or argon). The second process is describedin U.S. Pat. No. 4,234,435. US 2005/0202981 paragraphs 0014-0017 alsodescribe the reaction of polyisobutylene with maleic anhydrides to formsuccinated polyiosbutylenes of various structures.

The reaction product of polyisobutylene with maleic acid and/oranhydride (also known as polyisobutylene succinic anhydride) can vary incomposition depending on the molar ratio of maleic anhydride topolyisobutylene and the reaction conditions. Using the number of molesof maleic anhydride is from 1 to 2, 3 or 4 relative to the number ofmoles of polyisobutylene. Thus, the number of maleic (sometimes referredto as succinic) anhydride groups added to each polyisobutylene can varyfrom 1 to 4 and usually varies from 1 to 2 or 3. The mgKOH/g gives anindication of the number of potential carboxylic acid groups derived orderivable from the ring opening the maleic anhydride. The acid number asused herein represents the number of acid groups on the polyisobutylenealong with 2 times the equivalents of non-opened anhydride groups on thepolyisobutylene. A factor of 2 is used on the anhydride groups becauseeach anhydride is capable of forming 2 acid groups when the anhydridering is opened. Usually the reaction product is also characterized bythe number average molecular weight of the polyisobutylene or the numberaverage molecular weight of the reaction product. If one has both thenumber average molecular weight of the polyisobutylene and the acidnumber, one can calculate the relative number of carboxylic acid groupsper polyisobutylene chains.

The reaction product of polyisobutylene with maleic acid and/oranhydride (e.g., polyisobutylene succinic anhydride) is also referred toas hydrocarbyl-substituted acylating agent in the literature. In thisdisclosure, it is preferred to functionalize the anhydride ordicarboxylic acid with a non-polymeric amino ether/alcohol forming anester, amide and/or salt linkages (including mixtures thereof), in somecases the amide linkage may convert to imide linkage when thenon-polymeric amino ether/alcohol contains a primary amine. In theliterature, the hydrocarbyl-substituted acylating agent can have anumber average molecular weight of 500 to 2500 or 500 to 2000 g/mole.The hydrocarbyl substituent can be derived from an olefin or polyolefin.The polyolefin can be a homopolymer of a single C₂-C₁₀ olefin such asfor example isobutylene or a copolymer of two or more C₂-C₁₀ olefinssuch as for example ethylene and propylene and optionally butadienenon-polymeric amino ether/alcohol.

The non-polymeric amino ether/alcohol desirably has a amine group andhydroxyl or ether group(s) (such as one or two) and is according to theformula:

R₁ is a C₁₋₁₆ hydrocarbyl chain, preferably C₁₋₈ hydrocarbyl chain, morepreferably a C₂, hydrocarbyl chain. Wherein the hydrocarbyl chaincontains at least one hydroxyl or C₁₋₄ ether group, preferably hydroxylgroup and optionally contains a tertiary amine or ether group;

m is 1-2, preferably 2;

R₂ is a C₁₋₁₆ alkyl, preferably C₁₋₈ alkyl, more preferably a C₂ alkylchain optionally containing aromaticity if it has 6 or more carbonatoms, and/or optionally aliphatic portions; preferably R₂ is onlyaliphatic, optionally containing an ether linkage;

t: is 0-1;

q: is 1-2; and

t+m+q=3.

Examples of non-polymeric amino ether/alcohol include, but are notlimited to, diethanolamine, 2-(methylamino)ethanol,2-(2-aminoethoxy)ethanol, 3-amino-1,2-propanadiol, 6-amino-1-hexanol,2-(butylamino)ethanol, N-benzylethanolamine, bis(2-methoxyethyl)amine,N-(3-aminopropyl)diethanolamine, and N-(3-aminopropyl)diethanolamine.

The reaction between these two components (PIBSA and non-polymeric aminoether/alcohol) is then carried out at a molar ratio of 0.9:1 to 1.1:1 ofsuccan anhydride groups of the PIBSA with a non-polymeric aminoether/alcohol. And is carried out by heating both materials to 50-150°C., preferably less than 100° C., preferably less than 80° C. for 1-24hours, preferably 1-4 hours under a nitrogen blanket, optionally in thepresence of a diluent such as mineral oil, e.g., Exxsol D140. Completioncan be confirmed by IR spectra with the anhydride peaks at 1860 and 1780cm⁻¹ disappearing.

The PIBSA and the non-polymeric amino ether/alcohol react together toform a mixture of ester and amide bonds generating acid groups, andleaving residual amines and ethers/alcohols. The residual amines mayform salt bonds with the generated acids. Some imides may also be formedwhen primary amines are used.

In a preferred embodiment of the invention, the hydrocarbyl substituentis derived from a polyisobutylene which can have a vinylidene content ofterminal double bonds that is low at 30% or less or that is high at 50%or more. The acylating agent can be derived from an alpha,beta-unsaturated monocarboxylic or polycarboxylic acid or reactiveequivalent thereof to include an anhydride or an ester or an acidhalide. Useful alpha, beta-unsaturated carboxylic acids or reactiveequivalents thereof include for example methyl acrylate, fumaric acidand maleic anhydride. In an embodiment of the invention, the alphabeta-unsaturated carboxylic acid or reactive equivalent thereof ismaleic anhydride. Methods to prepare a hydrocarbyl-substituted acylatingagent are well known and generally involve for example heating apolyisobutylene or chlorinated polyisobutylene and maleic anhydride at150 to 250° C., optionally in the presence of a promoter such aschlorine. One or sometimes more than one maleic group (succinicanhydride group after grafting) can be added to each polyisobutylenemolecule.

In one embodiment, it is desirable that at least 50, 75 or 85 mole % ofthe available combine anhydride and carboxylic acid groups remain in therespective acid or anhydride form and not react with additional species(such as alcohols, amino alcohols, amines, or cationic metals) untilmixed with the mixed metal oxides. It is believed in this embodimentthat the anhydride or carboxylic acid groups function as better anchorsto the mixed metal oxides than do salts, ester linkages, amide, or imidelinkages. In another embodiment it is desirable that at least 50, 75 or85 mole % of the measured acid number of the reaction product ofpolyisobutylene with maleic acid and/or anhydride be in the carboxylicacid form when combined with the mixed metal oxide. In this embodiment,it is believed that the carboxylic acid group forms a better anchoringgroup than the anhydride group or other derivatives of the acid oranhydride.

In another embodiment, the ink is of the type to be printed with digitalversus analog technology and from an ink jet printer of the kindincluding piezo, thermal, acoustic and electrostatic mechanism to propelthe ink from the printhead. Preferably, the printers utilized with theseinks are of the piezo or electroacoustic drop on demand (DOD) type.

In another embodiment, the ink is printed on a substrate comprisingeither a ceramic object, e.g., tile or article including plates, bowls,saucers, cups, decorative ceramics, roofing tiles, or a glass substrate,e.g., pane or article such as a drinking glass, container, cup, etc.

Another embodiment is the ink jet ink is printed on a substrate, e.g.,ceramic tiles, by single pass inline and glass articles by multi passoff line DOD printers.

The particulate solids are mixed metal oxides used in the coloration ofceramic tiles. A particular highlight includes the dispersion of metalcontaminants present within the colored mixed metal oxide inorganicpigments to produce a more homogeneous color shade pattern free fromstreaks and striations caused by metal impurities and providing a muchbrighter shade.

The invention relates to the use of a class of dispersants in ceramicink jet inks formulations, to dispersions containing such dispersantstogether with a particulate solid (mixed metal oxides) and a continuousnon-polar organic (hydrocarbon) medium (which can comprise aliphatichydrocarbon, non-polar fatty acid esters, and various blends thereof),and compositions comprising a particulate solid, a continuous medium anda dispersant and to their use in ceramic ink jet inks and mill-bases.

Coloration of ceramic tiles by ink jet inks is a rapidly growingtechnology and providing stable ink jet ink dispersions of mixed metaloxides with D₅₀ particle sizes below 600 nm in various continuous mediumwithin a short milling time has been problematic.

Using the dispersant of the current application has provided stable inkjet ink dispersions containing mixed metal oxides with low particlesizes in a much reduced milling time, better filterability of thedispersions leading to increased millbase yield and reduction of waste,much brighter shades and better dispersion of metal impurities found inthe mixed metal oxides.

According to the present invention, there is provided a compositioncomprising a particulate solid, a continuous medium (non-aqueous), and adispersing agent having reaction product of polyisobutylene with maleicacid and/or anhydride and subsequent reaction with a non-polymeric aminoether/alcohol; used as or in part as an ink jet ink for the colorationof ceramic tiles using an ink jet ink printer.

The particulate solids can be mixed metal oxides or mixtures thereof,which may contain undesired metal impurities from abrasive wear of themilling equipment or beads, present as contaminants and/or as impuritiesfrom the milling process.

The continuous media can be aliphatic hydrocarbon media (desirably theamount of aromatic hydrocarbon is less than 20, more desirable less than10, and preferably less than 5 wt. % of the hydrocarbon media), orblends thereof.

In one embodiment, non-polar organic (hydrocarbon) liquids are compoundscontaining aliphatic groups or mixtures thereof, preferably hydrocarbonsof 6 to 40 carbon atoms. The non-polar organic liquids includenon-halogenated aliphatic hydrocarbons (e.g., linear and branchedaliphatic hydrocarbons containing six or more carbon atoms both fullyand partially saturated).

In one embodiment, the preferred solvents used in the dispersion of theceramic mixed metal oxides with the dispersant reaction product ofpolyisobutylene with maleic acid and/or anhydride dispersants includepetroleum distillate (various boiling fractions including C₁₆₋₂₀ alkanesmixtures and cyclic alkanes), paraffin, mineral spirit, or mixturesthereof.

In one embodiment, the non-polar organic (hydrocarbon) liquid media isfree of water. As used herein, the expression substantially free ofwater indicates that the reaction contains a minimal amount of water,for instance contaminant or trace amounts not removed in normalprocessing. In one embodiment, the non-polar organic (hydrocarbon)liquid of the continuous medium optionally contains less than 7, moredesirably less than 5, and preferably less than 1 wt. % of water basedon the weight of the dispersion. In one embodiment, the continuous mediais free of water.

By the term “polar” in relation to the organic liquid, it is meant thatan organic liquid is capable of forming moderate to strong bonds asdescribed in the article entitled “A Three Dimensional Approach toSolubility” by Crowley, et al. in Journal of Paint Technology, Vol. 38,1966, pg. 269. Polar organic liquids generally have a dielectricconstant of 5 or more as defined in the abovementioned article.Non-polar liquids typically have a dielectric constant of less than 5.

Advantages of the current dispersing agent would be reduced millingtime, better dispersion of any metal impurities and/or contaminantsleading to homogeneous colored shades, brighter shades, better particlesize stability during storage, improved filterability and increaseddispersion/ink yield, reduced syneresis, reduced sedimentation and lessphase separation between the dispersed phase and continuous phase duringstorage.

A preferred particulate solid is mixed metal oxides used in thecoloration of ceramic tiles and glass. For the purposes of thisinvention, mixed metal oxides is interpreted as the solid containing atleast two different metals in the same or different oxidation states. Aparticular improvement from using the dispersants of this disclosureincludes the reduction of metal contaminants derived from abrasive wearof the milling equipment as the particular mixed metal oxides are hardto mill and require hard ceramic beads to mill these pigments. Thedispersants of this disclosure tend to shorten the milling time requiredto meet a desirable particle size. When the total milling time on beadmills using hard ceramic beads is reduced, the amount of abrasive wearon both the beads and the internal components of the mill is generallyreduced. Reducing the abrasive wear means less metal contaminants fromthe internal parts of the mill and the beads are introduced into themilled product. While metal contaminants are usually low in color inmost pigment binder based coatings, metal contaminants can drasticallyaffect color shade and color intensity in mixed metal oxides fired above600° C. for coloring ceramic articles and glass.

This disclosure also provides for a method of milling a mixed metaloxide pigment having an initial volume average particle diameter inexcess of 2 micron in a non-polar organic hydrocarbon) continuous phaseto an average particle size of less than 700 or 600 nanometers, saidprocess comprising:

a) blending a non-polar organic (hydrocarbon) medium, a mixed metaloxide pigment, optionally including a vitreous glaze material, having a50% volume average particle diameter in excess of 2 micron, and adispersing agent being a reaction product of polyisobutylene with maleicacid and/or anhydride further reacted with the non-polymeric aminoether/alcohol;

b) milling said mixed metal oxide pigment dispersed with said dispersingagent in said non-polar organic (hydrocarbon) medium using a bead mill;optionally at a milling rate of 0.4 to 8 kw/hour per kg of particulateor 5 mins to 60 hours milling time; and

c) confirming that the average particle diameter of 50% volume of theparticles is less than 600 nanometers. In one embodiment, theparticulate material can have a dry powder volume average particlediameter D₅₀ in excess of 2 micrometer at the start of the millingprocess.

This disclosure also provides a process for digitally printing onceramic articles or glass articles using an ink jetted through a nozzleby:

a) providing a mixed metal oxide pigment dispersed in a continuousnon-polar organic (hydrocarbon) medium with a dispersing agent being areaction product of polyisobutylene with maleic acid and/or anhydridefurther reacted with the non-polymeric amino ether/alcohol, and

-   -   wherein the particulate solid is a mixed metal oxide pigment        that develops its color intensity and hue after firing at        elevated temperatures;

b) jetting said mixed metal oxide dispersed in said continuous mediumusing said dispersing agent according to a digital image to form animage on a substrate (optionally on a pre-glaze layers on a ceramicsurface) that develops color intensity on said ceramic or glass articleduring firing; and

c) optionally applying a glaze over said digital image; and d) firingsaid ceramic article at a temperature above 600° C. or tempering orannealing said glass article at a temperature above 400° C. to causesaid mixed metal oxide to develop its color.

The pre-glaze layer can be applied using traditional methods such as acurtain coater or spray coater. Alternatively, the pre-glaze layer couldbe applied using ink jet printer technology. Said pre-glaze layer abovecan be a single pre-glaze layer or multi pre-glaze layers. A pre-glazelayer is usually applied to help smooth the surface of a ceramicsubstrate and optionally adds components to the surface of the ceramicor glaze to optimize properties of the finished ceramic article. Thepre-glaze layer(s) can include colorants.

It has been found that certain dispersants show excellent ability todisperse inorganic pigments (particularly those mixed metal oxides) toproduce colloidally stable non-aqueous dispersions, non-aqueous ink jetink dispersions and final non-aqueous ink jet inks for the coloration ofceramic tiles or glass using ink jet ink printers. Thus, according tothe present invention, there is provided an ink jet ink compositioncomprising a mixed metal oxide particulate solid, a continuous mediumand a dispersing agent being a reaction product of polyisobutylene withmaleic acid and/or anhydride further reacted with a non-polymeric aminoether/alcohol.

INDUSTRIAL APPLICATION

Coloration of ceramic tiles by ink jet ink technology is a rapidlygrowing application due to the variety and quality of images availablefor digital printing via ink jet inks. The particle size of the mixedmetal oxides used in older printing processes for ceramic articles andtiles were often too large to easily pass through the nozzles of mostink jet printers. Providing colloidally stable ink jet ink dispersionsof mixed metal oxides with D₅₀ particle sizes below 600 nm in variouscontinuous medium within a short milling time has been problematic.

In one embodiment, the compound of Formula 1 is a dispersant for mixedmetal oxide pigments of the type used to color ceramic articles such asceramic tiles or glass where the pigments are going to be exposed tofiring at 600° C. and above to cause the pigments to go from a lowintensity color to an intense permanent color.

The particulate solid present in the composition may be any inorganicsolid material (such as a pigment or glaze forming compound which issubstantially insoluble in the non-polar organic (hydrocarbon) medium)and which after firing at elevated temperatures provides a desirablecolor. In one embodiment, the particulate solid is a pigment. In anotherembodiment, the particulate solid is or includes an aluminium or silicarich compound that helps form the glaze compound.

In one embodiment, the ink composition of the invention providesimproved jetting efficiency, reduce nozzle plugging, reduced settling,easier filterability, less frequent filter plugging, and more consistentjetting in applications where a mixed metal oxide pigment is jetted ontoa ceramic article, such as a ceramic tile, roofing tile, plate, saucer,bowl, etc., or on glass article such as a pane, drinking glass, or inaccordance with a digital image. In this application, the use of thedispersants of this disclosure result in low concentrations of metal andmetal oxide wear contaminants from the milling equipment andbeads/balls. In one embodiment, the composition provided lower pigmentparticle size, better colloidal stability, lower amounts of entrainedmetal from the internal mill surfaces and beads.

Preferred pigments for coloration of ceramic objects or glass arePigment Yellow 159 (Zr—Si—Pr, zircon praseodymium yellow or praseodymiumyellow zircon) such as BASF Sicocer® F Yellow 2200 and 2214; BASFSicocer F Pink 10307; Pigment Red 232 (Zr—Si—Fe zircon) such as BASFSicocer® F Coral 2300; Pigment Red 233 (Ca—Sn—Si—Cr, chrome tin pinksphene); Pigment Brown 33 (Zn—Fe—Cr, Spinel) such as BASF Sicocer® Brown2700 and 2726; Pigment Blue 72 (Co—Al—Cr, Cobalt Spinel blue); PigmentBlue 28 (Co—Al spinel) such as BASF Sicocer® Blue 2501; Pigment Blue 36(Co—Al spinel) such as BASF Sicocer® Cyan2500; Pigment Black 27(Co—Mn—Fe—Cr spinel) such as BASF Sicocer® Black 2900; and Pigment White12 (Zr—Si) such as BASF Sicocer® White EDT/AK-4409/2.

If desired, the compositions may contain other optional ingredients,e.g., resins (where these do not already constitute the organic medium),binders, fluidizing agents, anti-sedimentation agents, plasticizers,surfactants, anti-foamers, rheology modifiers, leveling agents, glossmodifiers and preservatives.

The compositions typically contain from 20 to 40 or 60% by weight of theparticulate solid, the precise quantity depending on the nature of thesolid and the relative densities of the solid and the continuous medium.For example, a composition in which the solid is an inorganic material,such as an inorganic pigment, filler or extender, in one embodimentcontains from 20 to 60% by weight of the solid based on the total weightof composition.

The composition may be prepared by any of the conventional methods knownfor preparing dispersions for coloration of ceramic articles fired above600° C. or for glasses annealed or tempered above 400° C. Thus, thesolid, the continuous medium and the dispersant may be mixed in anyorder, the mixture then being subjected to a mechanical treatment toreduce the particles of the solid to an appropriate size, for example,by ball milling, bead milling, gravel milling or plastic milling untilthe dispersion is formed. It is anticipated that a variety of particlesize and dispersing equipment can be used sequentially to minimize totalmilling time and expense, such that a large particle size pigment can bedispersed in a continuous media with the dispersant, an initial pre-mixor pre-mill grinding to a desired particle size range, and then transferto a bead type mill to further break down particulate particles into theD₅₀ 200-600 nanometer diameter (by volume average particle sizemeasurements).

In one embodiment, the beads used to mill the mixed metal oxide pigmentsare a ceramic bead rather than a metal bead. In further embodimentsusing ceramic beads, it is desirable that the ceramic beads arezirconium dioxide, yttrium stabilized zirconia, and/or silicon carbide.The beads are often 0.3 to 0.4 mm in diameter. The mills are oftenhorizontal bead mills and a popular supplier of the mills is Netzsch.The milling often targets a medium value of the particle sizedistribution where a volume average particle diameter of D₅₀ of 600 or300 nm or less and a D₉₀ of 800 or 500 nm or less is achieved. A D₅₀ of300 nm is a value in which 50% of the particles present in a particlesize distribution have diameters greater than 300 nm and 50% havediameters below 300 nm. Milling times are from about 5 minutes to 60hours, and more desirably from about 5 minutes to 48 hours. In oneembodiment, the energy used by the mill over the time period disclosedabove ranges from 0.4 to 8 kw/hour per kg of particulate produced togive D₅₀ particles in the range disclosed above. The mills may use someclassification methods to separate smaller particles from largerparticles and then mill the different sized particles to differentextents. Solvent may be added during milling to control viscosity,solids contents, etc. Dispersant may be added sequentially orcontinuously during milling as milling increases the surface area of agram of pigment and it reduces its D₅₀ average particle size from inexcess of 2 micron to less than 600, 500 or 300 nanometer.

While not wishing to be bound by theory, it is hypothesized that somedispersants are more effective at getting to newly created surfacesduring milling and stabilizing the new surfaces of fractured particlesagainst aggregation into larger particles. Some dispersants are betteranchored to particulates and better colloidally stabilize the particlesduring high energy mixing against agglomeration into larger sizedparticles.

In one embodiment, the dispersants being a reaction product ofpolyisobutylene with maleic acid and/or anhydride further reacted withnon-polymeric amino alcohol or amino ether (also described as aminoether/alcohol) can be used to make self-dispersable or re-dispersablepigment concentrates for coloring ceramic articles. In this embodiment,a continuous media that can be evaporated off or removed bycentrifugation can be used to conduct the milling and then the pigmentwith dispersant thereon can be concentrated, stored, shipped etc., untilneeded in dispersion form. If a composition is required comprising aparticulate solid and a dispersant being a reaction product ofpolyisobutylene with maleic acid and/or anhydride further reacted withnon-polymeric amino ether/alcohol in dry form, the organic liquid istypically volatile so that it may be readily removed from theparticulate solid by a simple separation means such as evaporation. Inone embodiment, the composition comprises an organic (hydrocarbon)liquid continuous media having the prescribed low levels of water orfree of water.

The compositions of the invention are suitable for preparing mill-baseswherein the particulate solid is milled in an organic (hydrocarbon)liquid in the presence of a compound being a reaction product ofpolyisobutylene with maleic acid and/or anhydride further reacted withnon-polymeric amino ether/alcohol. These mill-bases can be mixed inprecise ratios to form colorants for ceramic articles having specificcolor intensity and shade. It is anticipated that colorants forapplication by ink jet technology will comprise at least 3 and up to 12different colors that can be ink jetted to form a variety of colors,shades, intensities, etc., on ceramic articles after firing at 600° C.or more.

Typically, the mill-base contains from 20 to 60% by weight particulatesolid based on the total weight of the mill-base. In one embodiment, theparticulate solid is not less than 20 or not less than 25% by weight ofthe mill-base. Such mill-bases may optionally contain a binder addedeither before or after milling.

The amount of dispersant in the mill-base is dependent on the amount ofparticulate solid but is typically from 0.1 or 1 to 20% by weight of themill-base.

Dispersions and mill-bases made from the composition of the inventionare particularly suitable as pigment dispersions for use insolvent-based inks for ceramic articles especially ink jet printedceramic objects that are fired at 600° C. or above to develop thepigment color characteristic such as wall and floor tiles.

This disclosure also includes a process for digitally printing onceramic article or glass article using an ink jetted through a nozzleby:

a) providing a mixed metal oxide pigment dispersed in a continuousnon-polar organic (hydrocarbon) medium with a dispersing agent being areaction product of polyisobutylene with maleic acid and/or anhydridefurther reacted with non-polymeric amino ether/alcohol;

b) jetting said mixed metal oxide dispersed in said continuous mediumand said dispersing agent according to a digital image to form an imagethat develops on said ceramic article or glass article during firing(wherein said ceramic article optionally has one or more pre-glazelayer(s) thereon prior to receiving said digital image);

c) optionally applying a glaze over said digital image; and

d) firing said ceramic article or glass article at an elevatedtemperature to cause said mixed metal oxide to develop its color.

The coatings or inks made from mixed metal oxide dispersions anddispersants of this specification differ from conventional organicbinder based coatings and inks in two additional details. In a preferredembodiment, the binder (if any) in the coatings and inks of thisspecification are substantially (e.g. ≥90 wt. %, ≥95 wt. %, or ≥99 wt. %based on the dried and heat treated coating or ink) inorganic materialrather than organic material. A second significant difference is thatthe dispersants of this specification are significantly volatilized orburned away (e.g. ≥80 wt. %, ≥90 wt. %, or ≥99 wt. % of the dispersantis volatilized or burned away based on the weight of the dispersantprior to heat treatment). Thus, in organic binder systems the organicdispersant is retained in the final ink or coating as an interfacebetween the binder and the particulate matter. In the inks and coatingsof this specification, the dispersant is only present until the heattreatment of the article and the coating or ink to melt and fuse the inkto the ceramic or glass substrate. After the heat treatment, thedispersant is substantially burned away or volatilized so that thecoating or ink and the particulate (e.g., pigment (mixed metal oxide) orvitreous material of the glaze) is substantially free of any organicdispersant at the interface between the particulate and the inorganicmaterials of the ceramic or glass.

Ceramic articles will generally mean a variety of useful and decorativeitems formed from clay and porcelain that develop additional strengthfrom an elevated temperature treatment (such as about 400 to about 1200°C.) that fuses the inorganic material providing additional mechanicalstrength and resistance to liquids. They include, but are not limitedto, tiles in various sizes and shapes, cups, jars, crocks, other storagevessels, bowls, plates, utensils, jewelry, bricks, floor, ceiling, andwall tiles, etc. The ceramic articles can be intended for use inside adwelling or for exterior use such as in building construction.

Glass articles include functional and decorative glass articles. Glassdiffers from ceramic in that ceramic is generally translucent at bestwhere glass (unless intensely colored) is generally transparent inthicknesses of about 0.5 mm such that size ten type can be read throughglass panes under normal sunlight conditions. For the purpose of thisspecification, glass articles will generally have high concentrations ofsilica (e.g., SiO₂) of at least 50% by weight based on the entire glassportion of the article. Examples of glass compositions includelead-oxide glass at 59 wt. % silica, 2 wt. % Na₂O, 25 wt. % PbO, 12 wt.% K₂O, 0.4 wt. % alumina and 1.5 wt. % Zn; sodium borosilicate glasswith about 81 wt. % silica, 12 wt. % B₂O₃, 4.5 wt. % Na₂O, and 2 wt. %Al₂O₃; soda-lime-silica window glass with about 72 wt. % silica, 14.2wt. % Na₂O, 25 wt. % MgO, 10 wt. % CaO, and 0.6 wt. % Al₂O₃; and fusedsilica glass with 95+wt. % silica. Glass articles can generally include,but is not limited to, glass panes (including curved and non-flatpanes), tubes, vials, bottles, beakers, flasks, glasses, cups, plates,bowls, pans, lenses, vessels, jars, spheres/balls, etc. In the past,screen printing has been used to decorate some glass containers andarticles with mixed metal oxide type pigments formed into an inorganicink. These can somewhat permanently identify the contents with source,content, or trademark identification.

The following examples provide illustrations of the invention. Theseexamples are non-exhaustive and are not intended to limit the scope ofthe invention.

EXAMPLES List of Dispersant Ingredients

PIBSA A: polyisobutlyene succinate ended with a MW of 1000 which wasmade via a direct addition route.

PIBSA B: polyisobutlyene succinate ended with a MW of 1000 which wasmade via a chloride route.

PIBSA C: polyisobutlyene succinate ended with a MW of 550 which was madevia a direct addition route.

Diethanolamine: Ex Sigma Aldrich

SN100: Ex Fred Holmberg

Exxsol D140: Ex ExxonMobil

2-(Methylamino)ethanol: ex Sigma Aldrich

2-(2-Aminoethoxy)ethanol: ex Sigma Aldrich

3-Amino-1,2-propanadiol: ex Sigma Aldrich

6-Amino-1-hexanol: ex Sigma Aldrich

2-(Butylamino)ethanol: ex Sigma Aldrich

N-Benzylethanolamine: ex Sigma Aldrich

Bis(2-methoxyethyl)amine: ex Sigma Aldrich

N-(3-Aminopropyl)diethanolamine: ex Tokyo Chemical Industry UK Ltd.

Tris(hydroxymethyl)aminomethane: ex Sigma Aldrich

N-Methyl-D-glucamine: ex Sigma Aldrich

Dispersants

Comparative example 1: Polyester B from U.S. Pat. No. 3,778,287

Method

PIBSA, amine and solvent are charged to reaction vessel and heated to70° C. under a blanket of nitrogen, reaction mixture stirred for 2hours, reaction then poured off.

TABLE 1 Dispersants Dispersant PIBSA Amine Solvent  1 PIBSA A, 130.9Diethanolamine 25.81 SN100 156.71 parts parts by wt. parts  2 PIBSA B14.72 Diethanolamine 1.99 parts SN100 15.29 parts parts  3 PIBSA C 65.45Diethanolamine 10.75 Exxsol D140 76.2 parts parts parts  4 PIBSA A,2-(methylamino)-ethanol Exxsol D140 63.89 58.95 parts 4.94 parts parts 5 PIBSA A, 2-(2-Aminoethoxy)- Exxsol D140 52.9 47.35 parts ethanol 5.55parts parts  6 PIBSA A, 3-Amino-1,2-propandiol Exxsol D140 56.78 51.54parts 5.24 parts parts  7 PIBSA A, 6-Amino-1-hexanol 6.89 Exxsol D14059.6 52.71 parts parts parts  8 PIBSA A, 2-(butylamino) ethanol ExxsolD140 58.72 51.93 parts 6.79 parts parts  9 PIBSA A, N-Benzylethanolamine9.2 Exxsol D140 63.82 54.62 parts parts parts 10 PIBSA A,Bis(2-methoxyethyl)- Exxsol D140 63.13 54.97 parts amine 8.16 partsparts 11* PIBSA A, Diethanolamine 6.28 parts Exxsol D140 59.84 53.56parts parts 12# PIBSA A, N-(3-Aminopropyl) di- Exxsol D140 410.7 1403.0parts ethanolamine 242.8 parts parts 13** PIBSA A,Tris(hydroxymethyl)aminomethane Exxsol D140 164.6 145.01 parts 19.59parts parts 14## PIBSA A, N-Methyl-D-glucamine Exxsol D140 199.73 164.03parts 35.70 parts parts *Reaction carried out at 150° C., not 70° C.#Reaction carried out at 110° C. for 1 hour, then 150° C. for 3 hours.**Reaction carried out at 70° C. for 1 hour, then 100° C. for 6 hours,then 150° C. for 4 hours. ##Reaction carried out at 70° C. for 1 hour,then 100° C. for 1 hour, then 140° C. for 2 hours, then 150° C. for 4hours. And, final reaction mixture passed through a 150 NM filter toremove a small amount solid material.Applications Testing

Pigment Brown Dispersions—Premix

Dispersions are prepared by dissolving dispersants (16.8 parts) in ExsolD140 (ex.ExxonMobil) (700 parts). Colorificio Brown 79105D pigment (280parts) was added to each mixture and each were premixed using a sawtooth impeller at 2000 rpm for 60 minutes.

Each premix was then milled using a Netzsch LAbStar/Mini Mill and a“mini” grinding chamber (0.16 l) under the following conditions: a 75%bead charge of 0.3-0.4 mm YTZ beads at 4000 rpm, a pump speed of 15 rpmand a mill temperature of 30-40° C.; for 150 minutes. Particles sizeswere obtained by taking a sample of the milling dispersion (0.04 parts)and diluting in toluene (8 parts) and measuring the particle size on aNanotrac DLS particle size analyzer. Viscosity measurements of thedispersions were obtained using a TA 200EX Rheometer with a 2° aluminiumcone at a temperature of 25° C.

Filterability was carried out by pushing 25 ml of the millbase through a5 ul syringe filter until no more sample would come through the filteror no more material remained.

Particle Size (PS) percentage change was carried out by measuring theparticle size of the ink imminently after milling and then storing theink for 3 weeks at 40° C. and then re-measuring the particle size.

Sedimentation ratios were carried out on ink that had been stored for 3weeks at 40° C. and this was done by simply decanting and weighing thesupernatant. Redispersion was carried out by placing the ink on rollersat 120 rpm for 10 minutes. It is an object of this disclosure to developdispersants to minimize increases in particles sizes after dispersionand/or to minimize sedimentation of mixed metal oxides during storage.

TABLE 2 Dispersion Characteristics Sedimen- Sedimen- % PS % PS tation wt% tation wt % Inital change change after without Agent Filtrability D₅₀D₉₀ redispersion redispersion Dispersant 1 19 ml 4% 1%    0% 20.44%Dispersant 2 25 ml 9% 7% 26.26% 69.58% Dispersant 3 16 ml 14% 3% 10.02%47.76% Dispersant 4 19 12% 1% 9.83 35.30 Dispersant 5 23 6% 4% 18.4450.94 Dispersant 6 24 4% 1% 0.00 13.56 Dispersant 7 24 0% 1% 9.98 34.43Dispersant 8 25 6% 1% 22.88 61.44 Dispersant 9 24 7% 12% 18.91 48.19Dispersant 23 2% 14% 27.00 57.55 10 Dispersant 24 6% 2% 5.82 41.67 11Dispersant 23 8% 11% 34.47 74.41 12 Comparative 14 ml 12% 16% 28.93%84.67% Example 1

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications, thereof,will become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

What is claimed is:
 1. A process for digitally printing on ceramicarticle or glass article substrate using an ink jetted through a nozzleby: a) providing a mixed metal oxide dispersed in a continuoushydrocarbon medium with a dispersing agent, said dispersing agentcomprising a reaction product of polyisobutylene with maleic acid and/oranhydride further reacted with an amino ether/alcohol to form at leastone of ester, amide and salt linkages between the amino ether/alcoholand said reaction product of maleic acid and/or anhydride thereof withpolyisobutylene; b) jetting said mixed metal oxide dispersed in saidcontinuous medium using said dispersing agent onto said substrate toform a pigmented digital image, wherein said pigmented digital image onsaid substrate develops into a colored image upon firing said ceramicsubstrate or heating said glass substrate to provide tempering orannealing; c) optionally applying a glaze over said digital image; andd) heating said ceramic article at an elevated temperature or heatingsaid glass article to anneal or temper it, wherein said image from mixedmetal oxide develops color intensity upon heating.
 2. The process ofclaim 1, wherein the mixed metal oxide pigment that develops its colorintensity and hue after firing at 600° C. or above for a ceramicsubstrate or 400° C. or above for a glass substrate.
 3. The process ofclaim 1, wherein said mixed metal oxide is at least one ceramic pigmentof mixed metal oxides which contain a combination of two or moreelements in cationic form selected from the group of Al, Mg, Ca, Cd, Co,Cr, Fe, In, Mn, Ni, Pr, Sb, Se, Si, Sn, Ti, V, Zn and Zr.
 4. The processof claim 1, wherein said reaction product of polyisobutylene with maleicacid and/or anhydride has a number average molecular weight from 500 to2500 g/mole and an acid number from 40 to 200 mgKOH/g of dispersant andsaid non-polymeric amino alcohol/ether has the formula:

wherein R₁ is a C₁₋₁₆ hydrocarbyl chain, wherein the hydrocarbyl chaincontains at least one hydroxyl or C₁₋₄ ether group and optionallycontains a tertiary amine; m is 1-2; R₂ is a C₁₋₁₆ alkyl, optionallycontaining aromaticity, R₂ optionally containing an ether linkage; t is0-1; q is 1-2; and t+m+q=3.
 5. The process of claim 1, wherein saidhydrocarbon continuous phase comprises an aliphatic hydrocarbon andoptionally up to 20 wt. % of aromatic hydrocarbon, based on the weightof the continuous phase.